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-ray dust monitor for highly-concentrated airborne contaminantsSagawa, Naoki; Fujisawa, Makoto; Hosomi, Kenji; Morishita, Yuki; Takada, Chie
Hoken Butsuri (Internet), 58(3), p.135 - 140, 2023/11
Radioactivity concentrations of airborne dust are important measurements because they are used to protect workers from intakes and to assess internal exposure doses. Therefore, we developed a portable -ray dust monitor by using an ultra-thin plastic scintillator, which is designed for continuous monitoring of highly-concentrated airborne contaminants (
10
Bq/cm
, equivalent to 30 times larger than the derived air concentration of 
Sr) such as a decommissioning work in the Fukushima Daiichi Nuclear Power Plant. From the performance test results, it is evaluated that the developed portable -ray dust monitor is functional in continuous monitoring with an airborne concentration of 1 Bq/cm.
Nakamura, Kazuo*; Jiang, Y.*; Liu, X.*; Mitarai, Osamu*; Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Hasegawa, Makoto*; Tokunaga, Kazutoshi*; Zushi, Hideki*; et al.
Fusion Engineering and Design, 86(6-8), p.1080 - 1084, 2011/10
Times Cited Count：4 Percentile：32.36(Nuclear Science & Technology)Ohara, Yoshihiro; Tanaka, Shigeru; Akiba, Masato; Araki, Masanori; Fujisawa, Noboru; Hanada, Masaya; Inoue, Takashi; ; Mizuno, Makoto; Okumura, Yoshikazu; et al.
JAERI-M 91-052, 176 Pages, 1991/03
no abstracts in English
Yamamoto, Shin; Ohara, Yoshihiro; Tani, Keiji; Nishio, Satoshi; Okumura, Yoshikazu; Araki, Masanori; Azumi, Masafumi; R.S.Devoto*; Fujisawa, Noboru; Hitoki, Shigehisa*; et al.
JAERI-M 88-086, 183 Pages, 1988/05
no abstracts in English
Morishita, Yuki; Tomioka, Akifumi; Fujisawa, Makoto; Izaki, Kenji
no journal, ,
It is important to differentiate between natural and artificial radioactive materials such as plutonium in nuclear facilities. In this study, a scintillator-based alpha-particle detector was developed using YAP:Ce scintillator and Multi-Anode PhotoMultiplier Tube. The detector was used to measure various naturally occurring radioactive materials (NORM) samples including radon progeny, lead plate, lantern mantle, and radium ball. The measurement results were compared with Monte Carlo simulation calculations and were found to be in agreement. The energy resolution of the detector is 8.6%FWHM. In the measurement results of radon progeny, peaks of 
Bi (6.1 MeV), 
Po (7.7 MeV), and Po (8.8 MeV) can be observed. The lead plate contains 
Po and emits 5.3 MeV alpha particle. The simulation with the same energy was able to reproduce the actual measurement. The results showed the energy and distribution of the alpha particles emitted by the NORM samples. The study successfully demonstrated the capability of the developed alpha-particle detector in identifying NORM.
Morishita, Yuki; Sagawa, Naoki; Fujisawa, Makoto; Kurosawa, Shunsuke*; Sasano, Makoto*; Hayashi, Masateru*; Tanaka, Hiroki*
no journal, ,
This study reports the effects of different types of radiation on a high-resolution alpha imager, developed using an Electron Multiplying Charge-Coupled Device (EMCCD) camera. The imager was originally designed to visualize Pu oxide particles in decommissioning sites, where other types of radiation such as beta particles, gamma-rays, and neutrons are also present. The measurement of alpha particles, beta particles, gamma-rays, and neutrons were performed, and it was found that the EMCCD camera's sensor detected gamma-rays and neutrons. The discrimination method was based on the characteristics of the image distribution, where the image values were binarized and a Gaussian filter was applied to count the number of alpha particle spots. The results show that it is possible to discriminate between alpha and gamma (neutron) rays using the difference in intensity. The study provides important information for the development of radiation detection techniques in decommissioning sites.
Morishita, Yuki; Sagawa, Naoki; Fujisawa, Makoto; Kurosawa, Shunsuke*; Sasano, Makoto*; Hayashi, Masateru*; Tanaka, Hiroki*
no journal, ,
This study reports the effects of different types of radiation on a high-resolution alpha imager, developed using an Electron Multiplying Charge-Coupled Device (EMCCD) camera. The imager was originally designed to visualize Pu oxide particles in decommissioning sites, where other types of radiation such as beta particles, gamma-rays, and neutrons are also present. The study aims to confirm the effects of these radiations on the imager and to develop a discrimination method between alpha particles and other radiations. The measurement of alpha particles, beta particles, gamma-rays, and neutrons were performed. The discrimination method was based on the characteristics of the image distribution, where the image values were binarized and a Gaussian filter was applied to count the number of alpha particle spots. The results show that it is possible to discriminate between alpha and gamma (neutron) rays using the difference in intensity. The study provides important information for the development of radiation detection techniques in decommissioning sites.
Tomioka, Akifumi; Fujisawa, Makoto; Izaki, Kenji; Shioya, Satoshi
no journal, ,
When body contamination occurs, decontamination is carried out basically by wiping with wet paper rag, pouring large amounts of running water, and using detergents such as neutral detergents. However, it can be said that these methods do not reflect much of the technological progress to date. For example, we believe that more efficient body decontamination can be achieved by applying new technologies of the beauty care and health care field. In this study, we evaluated the decontamination effects of multiple commercially available detergents and microbubble showers that are expected to have decontamination effects, through tests using a particulate visualization system and tests using radioactive substances.
Fujisawa, Makoto; Tomioka, Akifumi; Izaki, Kenji; Shioya, Satoshi
no journal, ,
It is important to predict the spread of radioactive materials attached to workers' bodies. We evaluated the degree to which contamination remained after wiping off protective gear and the degree to which contamination was dispersed when it was removed. In the test, we applied fluorescent paint that simulates radioactive substances to protective gear, wiped it off with a wet rag, and removed the gear. And we photographed the fluorescent paint with a camera and evaluated the decontamination effect of wiping and the spread of simulated contamination. As a result of the test, we were able to evaluate the degree to which the protective gear was contaminated.
Cl
H
CSOFujisawa, Masashi*; Shiraki, Kosuke*; Okubo, Susumu*; Ota, Hitoshi*; Yoshida, Makoto*; Tanaka, Hidekazu*; Sakai, Toru
no journal, ,
The spin dynamics of the quasi-one-dimensional antiferromagnet CuClHCSO was investigated by the electron spin resonance (ESR). The system has a spin gap, but the direct ESR transition of the spin gap is forbidden due to the spin conservation law, because the spin gap is an energy gap between the singlet and triplet states. However, the direct ESR transition of the spin gap was observed for this material. The present study revealed that the origin of the direct ESR transition is the Dzyaloshinsky-Moriya interaction, and applying the selection rule of the angle-dependent ESR intensity, we successfully specified the direction of the interaction vector.
Imahashi, Atsushi; Hosomi, Kenji; Fujisawa, Makoto; Takada, Chie
no journal, ,
no abstracts in English
-particle detector designed for monitoring of airborne dust with high radioactivityFujisawa, Makoto; Sagawa, Naoki; Hosomi, Kenji; Morishita, Yuki; Takada, Chie
no journal, ,
no abstracts in English
